DOI: 10.1061/jmcee7.mteng-22958 ISSN: 0899-1561
A Method for Preparing Low-Temperature and High-Strength Recycled Cement Clinker
Pei Ge, Yang Song, Yunxiang Zhang, Zhihong Zhuo, Xiaohong Chen, Junwen Zhou Abstract
To convert concrete waste into low-carbon cementitious materials, this study employed
CaSO
4
as a mineralizer and
Al
2
O
3
as a supplementary component. Systematic investigations were conducted on the mineral composition, functional groups, and micromorphology of recycled calcium sulfoaluminate cement (RCSC) clinker, as well as key properties of RCSC hydration products. The results indicate that when only 2% by weight
CaSO
4
and 8% by weight
Al
2
O
3
were added to hardened cement powder (HCP), the compressive strengths of the hydration products were 50, 65, and 70 MPa at calcination temperatures of 1,300°C, 1,400°C, and 1,450°C, respectively. This approach not only achieves the recycling of concrete waste but also reduces both energy consumption and carbon emissions during recycled cement production. The significant strength enhancement of RCSC is attributed to the formation of substantial
Ca
4
Al
6
O
12
SO
4
(ye’elimite) from CaO,
CaSO
4
, and
Al
2
O
3
under high-temperature conditions. Upon hydration,
Ca
4
Al
6
O
12
SO
4
reacts to form ettringite (AFt), which interpenetrates and interweaves with calcium silicate hydrate (C─S─H) to construct a three-dimensional network structure. This network fills the internal pores of the hydration products and reinforces the cohesion of C─S─H. Additionally, a performance control method for RCSC based on three parameters (
C
m
,
P
, and
n
) is proposed, providing an important theoretical basis for its performance regulation.